Difference between PFO and ASA??

I was recently diagnosed with a PFO as well as an ASA with shunting.. I'm just wondering what the difference is between the two.. From what I've read they seem pretty similar, is that correct?? I was told to take a baby aspirin a day and to come back every two to three year for echos.

BTW, I also have a bicuspid aortic valve that was found at the same time as the PFO and ASA. I've also had two ablations for PVCs, the first was unsuccessful, the second was was a success and I'm PVC free for the first time in my life. I'm 28, not over weight, don't smoke and generally in good health other than the new found heart issues.. I do have chronic daily headache with break through migraine w/aura.. How concerned should I be with stroke??

Thanks, Beck